Investigation of the molecular epidemiology of West Nile virus at the human-animal interface in South Africa
West Nile virus (WNV) is an emerging, neurotropic zoonotic arbovirus that belongs to the Flaviviridae family and the Flavivirus genus. Since its discovery in 1937 in Uganda, Africa, WNV has continued to spread outside of its original geographic range and has now been named the most widespread cause...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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University of Pretoria
2022
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| Online Access: | http://hdl.handle.net/2263/84001 https://doi.org/10.25403/UPresearchdata.19181573.v1 |
| Summary: | West Nile virus (WNV) is an emerging, neurotropic zoonotic arbovirus that belongs to the Flaviviridae family and the Flavivirus genus. Since its discovery in 1937 in Uganda, Africa, WNV has continued to spread outside of its original geographic range and has now been named the most widespread cause of arboviral neurological disease, occurring on every continent except Antarctica. West Nile virus is maintained in nature through an enzootic bird-mosquito transmission cycle, with Culex (Cx.) univittatus as the principal vector in South Africa. Birds are used as sentinels for WNV in many countries, but in Africa birds seldom die or show signs of disease therefore alternative animals- such as horses- are used as sentinels for WNV. In equines, 90.00 % of symptomatically infected horses will develop neurological disease, and 35 % of infections are fatal. Besides horses, additional vertebrate hosts such as domestic animals, cattle, sheep, goats, and wildlife exist. In humans 80.00 % of WNV infections are asymptomatic, and usually between 1-10.00 % of cases will progress to neurological disease with a fatality rate of 10.00 %, although recent outbreaks in Europe have seen an increase in neurological disease manifestations up to 77.00 % and mortality rates of 40.00 %. This type of data is currently not available for South Africa. This study aimed to investigate the molecular epidemiology of WNV in South Africa using a One-health approach and reports on the active circulation of endemic lineage 2 strains amongst mosquitoes, animals, and humans. The burden of disease and association with neurological disease was identified through syndromic surveillance in animals and humans. Additionally, a next-generation sequencing (NGS) pipeline was developed to sequence WNV full genomes from clinical specimens. Chapter one provides an in-depth review, first starting broad with the topic of flaviviruses, then taking a closer look at WNV highlighting the importance of this virus as a pathogen of medical and veterinary importance. Chapter ... |
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